One who has surmounted such levels as Assholery, Grand Fuckerydom, and so on in such a way of varying degrees of Buttholism. A jewchebag is somewhat like a douchebag but is more concerned with monetary ideals than the douche.

N00B-"ZOMG you can't even spend, like, a hundred bucks on our Galaga Reunites tour tickets???"
Goyim-*sheeeennnnnhaaa* "No way dood, I have to deposit ALL my money to the Bank of Moses!"
N00B-"...You are such a jewchebag!!!1!one!!"

The kind of Jewish guy that gives all Jews a bad name. He womanizes about women he'll never have and brags about his elite financial status to anyone within earshot. He has gelled hair that borders on Guido-offensive and won't get off of his Blackberry.

Alternately: he can be the literary type. Obsessed with Phillip Roth and Woody Allen and thinks only white, straight Jewish men are worthy of awards, publications, his time, etc.

Did you hear Jeff talking about how he got his tickets free from the owner of the team? He mentioned it only eight times after talking about his 200k frequent flier miles. What a Jewchebag.